Bowling pin having decreased neck checking tendencies



April 26, 1955 R. M. CONKLIN ETAL 3,248 ,115

TENDENCIES BOWLING PIN HAVING DECREASED NECK CHECKING Filed March 27,1963 INVENTORS: Ma

United States Patent 3,248,115 BOWLING PIN HAVING DECREASED NECKCHECKING TENDENCIES Robert M. Conklin, Muskegon, Fred E. Satchel], GrandHaven, and Foster W. Berry, Muskegon, Micln, assignors to BrunswickCorporation, a corporation of Delaware Filed Mar. 27, 1963, Ser. No.268,301 6 Claims. (Cl. 27382) This invention relates tobowling pins andmore particularly relates to decreasing neck checking tendencies inbowling pins.

Bowling pins usedin such games as ten pins and duck pins are subjectedduring use to high stresses generated at or just below the minimumsection in the neck of the pin. Such high stresses, together with thenatural configuration of the tissue elements of a wood core, may oftenresult in'checking or failure in the wood core parallel to the woodgrains. Such checking is engendered by repeated impacts during use ofthe pin and/or by a single blow of sufliciently high magnitude toinitiate check type failures. Once the checks or splitting failures havebeen started in a pin, their growth or extension into the body of thepin or into the head section of the pin results in complete failure ofthe pin. Failure of pins due a prominent cause of shortened pin life.

In games in which bowling pins are used, the action of a pin isappreciably affected by the continuity of the structure of the pin. Whenneck check failures have progressed sufficiently, the sound or ring ofthe pin is adversely affected. Such deterioration in sound is wellrecognized by the bowler as being symptomatic of checked or failed pinsin which the reaction of the pin has deteriorated. As a consequencebowlers rightly refuse toplay such pins knowing that checked or failedpins givelower scores. Thus, the proprietor of a bowling establishmentmust replace such pins, at some expense.

It is a general object of this invention to provide a new and usefulbowling pin having markedly reduced neck checking tendencies.

It is a further object of this invention to decrease the neck checkingtendencies in wood core bowling pins by providing an increased amount ofvertical wood fiber adjacent the pin surface at the neck portion orregion of the P Another object of this invention is to provide increasedamounts of vertical wood fiber adjacent the surface of the neck of awood core bowling pin by oversizing the neck portion of the pin core; amore particular object is to provide densified vertical wood peripheralfibers at the neck of the core.

A further object of this invention is to provide a regulation sizecoated wood core bowling pin wherein the wood core is the primary stresscarrying element, having an increased amount of vertical wood fiberadjacent the core surface in the neck portion. I

It is still another object of this invention to improve the manufactureof bowling pins by increasing the section modulus of the neck portion ofthe pin by providing a greater than normal diameter in the neck portionand normal diameters in other portions of the core, and especially byproviding a neck core diameter which is between .100 and .125 inchoversized in diameter compared with the normal core neck diameter andrelative to the diameters of other portions of the core.

It is yet another object to improve the manufacture of plasticcoatedhardwood ten. pins bowling pins by 'to checking is currently a seriousproblem and constitutes Patented Apr. 26, 1966 neck portion of the pinto density the vertical wood fibers adjacent the surface, and especiallyto a maximum depth at and/or subjacent the minimum diameter of the neckportion to give densification of a maximum depth in the range of to Ainch from the surface within an area in the neck portion lying between 3and 8 inches from the top of the pin.

Further objects include the oversizing of the neck portion of a pinfollowed by coating processes such as include coating to a uniformthickness followed by removal of excess coating material in neck portionor applying a thinner coating at the neck portion of the core relativeto other portions of the core, whereby a pin of regulation size isproduced having an oversized core neck.

Additional objects will be apparent to those in the art from thefollowing descriptions and drawings in which:

FIG. 1 is a vertical cross-section through an embodiment of a regulationsize plastic coated bowling pin of this invention showing an oversizedneck portion;

FIG. 2 is a vertical cross-section through another embodimentof aregulation size plastic coated bowling pin of this invention showing adensified neck portion;

FIG. 3 is a cross-section of an embodiment of a regulation size plasticcoated bowling pin of this invention with an oversized densifiedneck;-FIG. 3A is an enlarged portion of the cross-section'of FIG. 3showing a stepped coating; and

FIG. 4 is a vertical cross-section through a regulation size plasticcoated hardwood core bowling pin. While this invention is susceptible ofembodiment in many different forms, there is shown in the drawings andwill herein be described in detail an embodiment of the inventiontogether with a modification thereof with the "oversizing the neckportion of a pin and thereafter applying sufiicient pressure to theexterior of the oversized understanding that the present disclosure isto be construed as an exemplification of the principles of theinvention'and is not intended to limit the invention to the embodimentsillustrated. The scope of the invention will be pointed out in theappended claims.

Turning now to FIGS. 1 through 4, there are illustrated threeembodiments (FIGS. 13) of regulation size ten pins bowling pins of thepresent invention and a conventional regulation size wood core plasticcoated bowling pin (FIG. 4) for purpose of comparison. In FIG. 1, thevarious sections or portions of a bowling pin are identified generallyas head 15, neck 16, shoulders 17, belly 18 and base 19. FIG. 1illustrates a pin having an oversized core neck section. The pinincludes a hardwood, e.g., maple, core 10 and a plastic coating 11, suchas ethylcellulose laid down in layers. Coating 11 is generally from0.050 to 0.095 inch thick over the surface of the pin except in the neckarea, where the neck area portion of the coating, as indicated at 11a,decreases to as thin as 0.008 to 0.015 inch thick. Reference numeral1012 refers to dotted lines showing normal core configuration, theportion outside of the dotted lines being the amount of the oversizingin the neck, i.e., excess hardwood at the periphery of the neck.

FIG. 2 illustrates another embodiment where the neck portion isdensified. Again, the illustrated bowling pin includes a hardwood core20 having a plastic coating 21, which is uniform over the pin. Referencenumeral 20a indicates the densified portion of the neck which decreasesThe oversized and densified neck region is indicated by referencenumeral 30a and the coating of decreased thickness, substantially asillustrated in FIG. 1, is indicated by reference numeral 31a. Thecoating 31a in the neck region is a stepped layer coating which will bemore fully discussed herein below.

FIG. 4 illustrates a conventional regulation size bowling pin having ahardwood core 40 and a plastic coating 41. The exterior dimension ofcoating 41 in FIG. 4 is of regulation size, as are the exteriordimensions of coatings 11, 21 and 31 in FIGS. 1, 2 and 3 respectively.Thus, the pins of FIGS. 1, 2 and 3, although of regulation exteriorsize, include additional wood in the neck area by substantiallyoversizing or oversizing and densifyingthe neck region.

In a plastic coated wood core bowling pin the wood core is the primarystress carrying element. The plastic coating, because of its physicalproperties, has practically no effect on carrying stresses or inhibitingneck checking since it carries or absorbs only a minute percentage ofthe longitudinal and shear stresses generated in the geometry of a pin.V

In accordance herewith, an improved pin is provided by niques as well asby solvent washing the neck to remove increasing the amount of verticalwood fiber adjacent the 7 surface in the neck region. This isaccomplished by oversizing the neck region. The oversized neck regionmay subsequently be densified, if desired, to provide a further increasein the amount of wood fiber in the neck region or to compress the neckto normal core size so that a relatively uniform plastic coating can beapplied over the pin core without having to subsequently remove part ofw p to head of the pin. a It is known that fiber stress is a func tionof the section modulus for a given moment. Thus,

increasing the size of the core neck diameter, in accord-v anceherewith, reduces fiber stress. However, the increase in size of thecore neck diameter is limited in that it is necessary to maintain thepin within the dimensions as established by governing bodies for bowlinggames. The larger radius of transition from the neckto shoulder and headreduces the stress concentration in the neck.

As indicated above, the oversized neck may be densified prior toapplying the plastic coating to the pin. Densification mayadvantageously be used to decrease the diameter of the oversized neckportion so that a plastic coating may be applied to the neck portion inthe same thickness as applied to other portions, thereby simplifying thecoating operation. In such instance, the core neck diameter may bedecreased by densification to the normal diameter of a core neck whilemaintaining the effective section modulus of the oversized neck,although the larger radius of transition would be lost. Alternatively,the wood core could be shaped to provide sufficient over sizing so thatafter densification the neck wouldremain of greater thannormal'diameter, but less than the regulation diameter for a finishedpin, thereby retaining the larger radius of transition and acquiring astill greater effective section modulus. V 7

Where the wood core of the pin is to be coated with plastic material, ifthe neck has beendensified sufiiciently to provide a normal neckdiameter, the usual coating methods may be employed. Accordingly acoating of rather uniform thickness, e.g., varying from about..050 to.095 or more preferably .060 to .065 inch in thickness may be providedon the pin with thickness varying slightly over the core surface.dipping, flow-coating, and the like.

However, where the core having a larger diameter than normal is coated,the plastic coating must be correspondingly thinner at the neck regionwith increased core thick- Such coatings are applied by A variety oftechniques may be used for providing coat-.

ings of reduced thickness in the neck regions. Such techniques includethe coating of the pin to a normally rela tively uniform thicknessfollowed by removal of excess plastic material to restore properdimensions to the pin:

by shaping, sanding, grinding, or other machining techundesiredthicknesses of coating. Another technique tor providing reduced coatingthickness at the neck is by placing only that amount of coating materialon the neck region as is desired. .This maybe done by stepped .coat- Iing or other methods for providing a lesser number of coating layer inthe neck region,- minimizing the coating build up in the neck region.niques usually provide a smooth coating in the neck area with a gentletransition into the coating above and below the neck, especially afterturning to remove irregularities in the coating.

Additionally, the in core can be partially di ped from eachend, e.g.,alternatingly, omittingvthe dipping of'the neck portion' for asufficient number of dippingsqto i provide a thinner-coating as desired.As another technique the neck area can be masked with tapes orstrippable coatings, which are insoluble in the plastic .coatingmaterial.

lying coats. These techniques usually provide a stepped coating in theneck area, which may be suflicient as produced or may be machined toprovide a smoother transition in, the neck coating, especially where the7 steps are steep. The stepped layers of coating, ma-

terial are illustrated by reference numbers 32 through 36 in FIG. 3A..As another technique, when using coating systems of lower viscosity,after the desired thickness or number of layers of coating has been.attainedin neck region.

the art. a Coating material compositions for use in coating bowling pinsare well known and any such compositions: are usable in accordanceherewith. For example thef coating may be a lacquer of ethylcellulose,nitrocellulose, cellulose acetate, epoxies, urethanes or the likeMultilayer coatings of difiering materials may be used if de-. sired.Reinforcingfabrics or other materials may be embedded within thecoating, e.g., by placing between coating layers during the coating ofthe pin. Additionally,

or alternatively, in order to further strengthen the neck of the pinagain'stchecking, a thin layer of reinforcing material may be laiddirectly against the wood fibers of the oversized or oversized andden'sified portionof" the neck prior to application of the coatingmateriaL-as is disclosed in copendingapplication Serial No. 268,300,

filed on March 27, 1963, and entitled, Pin Having 15E creased NeckChecking Tendencies.

The thinner coating in the neck region does not apprecia-bly detractfrom the appearance of the pin, so long as sufficient plastic coating isleft in the neck area to give a pleasing appearance and maintainphysical con- The above coating tech Such masking compositions areapplied at the proper level of film build up during the coating process,and upon completion of the coating process. the masks are removed fromthe pin thereby removing oven 7 present bowling pins. Such coatingsreadily permit a preferred increase in core diameter of between .100 and.125 inch in the area of maximum oversizing. This increase appreciablyreduces the neck checking in pins, being equivalent to approximately aten to fifteen percent increase in cross-sectional area in the neck;

Turning now to the densification of the wood fibers in the neck region,a concentration of peripheral fibrous material, i.e., at an adjacentouter surface of the neck,

is achieved by densification. The outer surface of the neck (slightlybelow the minimum diameter) usually carries the maximum-flexuralstrength resulting from impact of the pin; The ultimate strength of woodin tension compression and flexureis a function of density.

'Ihus, densification of the outer surface provides more material orfibers to reduce stress to a higher degree before checking occurs. Whenthe neck region is densified, 'the density of the fiber varies radiallyfrom inside 'the pin to the surface of the pin. The variation of densityincrease is from practically zero increase, i.e., any increase abovenormal densitiy being barely apparent,

to a maximum at the surface of the core. Thus, the concentration ordensification of the fibers in the pin is provided in a manner whichaffords the maximum increase in density at the surface, graduallydiminishing to .to improve the densification results by application ofglycerin, urea, phenols, various inorganic salts, minerals,

animal and vegetable oils, resins forming systems, or othercompositions.

More particularly, the densification of the neck section can be efiectedby placing a turned bowling pin body within die sections contoured togive densifica tion as desired. Twoor more die sections can be providedto act radially on the pin body, preferably with maximum pressure justbelow the minimum diameter. Either the pin or die can be rotated, ifdesired, during the densification process. Alternatively a hydraulicapparatus can be used for applying pressure to the neck section of thepin surface by injecting air or other fluid into a chamber having aflexible wall, e.g., rubber or leather, which transmits pressure fromthe chamber to the pin surface. In still another densificationprocedure, the pin is inserted between spaced roll form wheels and thepin is rotated with the spaced wheels pressing against the desiredlength and depth of densification. After densification of the neckregion, it is preferred that the neck be reshaped to removeirregularities in the surface which may be created by compression of thefibers and to assure smooth transition of the neck into the head andshoulder portions of the pin.

The oversizing and oversizing and densifyingof the wood portion of theneck of a pin in accordance herewith is provided somewhere between 3 and8 inches, and preferably between 4 and 7 inches, from the top of aregulation ten pins bowling pin. Preferably, the neck has a 6 maximumoversizing and/ or maximum density at or slightly below the minimumdiameter of the neck, i.e., about 5 to 6 inches from the top of the pinand the oversizing and density respectively each decrease graduallyabove and below the area of maximum oversizing or density. The length ofthe oversized and densified portions of the neck can be varied but isusually within the range of about 2 to 5 inches, although an actuallength of from 2 to 3 inches would be normally sufficient.

The bowling pins illustrated in FIGURES l and 2 and a control pin (asillustrated in FIGURE 4) of the same construction but without oversizingfor densification in the neck were tested in accordance with a rotatingbeam fatigue test technique adapted to test pin neck fatigue life. Thetest determines failure in a bowling pin by neck checking due tostresses set up in the pin. Briefly, in accordance with the testprocedure, the pin tested is rotated on its longitudinal axis whilemaintaining a fixed. moment (relative to the rotating pin) of 2400 in.lb. so that as the pin rotates, the tension and compression shifts insuch a manner to in effect rotate through the pin so that each portionof the neck surface is exposed to tension and compression in each cycleof pin rotation. The number of cycles before neck checking, i.e.,failure of the pin, is taken as the test result, indicative of abilityof the pin to withstand stresses in the direction of the longitudinalaxis. The results of the test were as follows:

Cycles Pin sample tested: before failure Control (FIGURE 4) 1,900 FIGURE1 100,000 FIGURE 2 4,400

The above data indicates marked improvement in the present bowling pins,and especially oversized pins, to withstand tension and compression.

In further testing, a set of each of the pins of FIGURES '1 and 2 and aset of control pins (as illustrated in FIG- URE 4) of the sameconstruction with the exception that the neck portion of the core wasneither oversized nor densified, were subjected to an acceleratedbowling test. Briefly, the test is cyclic and employs an automaticpinsetter, a ball throwing machine and a short length of bowling alley.In. each cycle the ball throwing machine ejects a ball at a preselectedspeed in a fixed direction into the set of bowling pins at the strikezone. Between hits, the automatic pinsetter resets the pins with randomorientation and random position of pins. The pinsetter automaticallyreturns the ball to the throwing machine after each hit to complete thecycle. The number of cycles before failure of all pins of the set isrecorded. The results are as follows: 1

Set of pins tested: Number of cycles Control (FIGURE 4 28,000 FIGURE 168,000 FIGURE 2 63,000

In view of failures of other portions of the pins, e.g., the belly,especially in the pin that was produced in accordance with the presentinvention, it was not possible to determine the true neck life on everypin of the set.

However, it is believed that the comparative results are indicative ofthe improvement in the present invention in the prevention of neckchecking during use.

As a more particular identification of a typical suitable oversize pincore configuration, e.g., as illustrated in FIG- URE 1, the followingtable gives dimensions of such a pin compared with dimensions of astandard core as illustrated in FIGURE 4. The core plus coatingdiameters given were the same for both pins.

Distance from Top Oversize Core Standard Core Core Plus Coatof15" HighCore, Diameter (Fig. Diameter (Fig. mg Overall in. 1), in. 4), in.Diameter, in.

The above dimensions were the general dimensions of the cores of thepins comparatively tested with results reported hereinabove.

It is an advantage of the present invention that there has been provideda new and useful bowling pin having having the prescribed externalconfiguration, said coating having a thickness in the neck area of thepin less than at other areas of the pin, and the ,core having peripheraldensified stress absorbing wood fibers in the neck area, said coatingbringing the external pin configuration to prescribed dimensions.

2. A regulation size plastic coated hardwood bowling pin comprising ahardwood core as the primary stress carrying element,'said hardwood corebeing smaller than the regulation size bowling pin and having anenlargement in the-neck section otthe core relative to other portions ofthe core defining a substantially greater amount of vertical Wood fiberadjacent the pin surface in the neck section of the core than in theneck section of the core 8 of .the corresponding uniformly plasticcoated wood core regulation size bowling pin and a generally uniformdensity plastic coating covering and bringing said core ing element anda plastic coating of generally uniform density on said core, saidhardwood cone having an ex-, 'terna'l shape generally corresponding tothat of the com- 1 plete pin butrof a smaller size suflicient to permitapplica- -tion of a' coating thereto, an excess of integral hardwood inthe core in neck section of said pin, said. excess hard- 7 woodproviding an oversized neck portion between three and eight inches fromthe top or said pirysaid. oversized i neck portion gradually tapering tonormal configuration at its upper and'iower ends, said coatingcomprising a coating of less than normal thickness over said oversizedneck portion and a coating of normal thickness over there! mainder ofsaid pin.

5. The bowling pin of claim 4 wherein said coating of normal thicknessis in the range of from about 0.50 to 0.95 inch in thickness and saidcoating of less than normal thickness is in the range of from about .008to .015 .inch' density at the upper and lower ends of the neck sectionand gradually decreases .to normal density interior-1y irom the surfaceof the neck section.

References Cited hythe Examiner.

UNITED STATES PATENTS 2,562,801 7/1951 McKenzie.

2.944321 7/1960 Mason 273-8.2. 3,024,819 '3/1962 Dosker 273-42 3,065,96611/1962 Egbert 273- 821 3,098,655 7/1963 Martin 27,3 82

RICHARD c. PINKHAM, Primary Examiner. DELBERT B. LOWE, Examiner.

2. A REGULATION SIZE PLASTIC COATED HARDWOOD BOWLING PIN COMPRISING AHARDWOOD CORE AS THE PRIMARY STRESS CARRYING ELEMENT, SAID HARDWOOD COREBEING SMALLER THAN THE REGULATION SIZE BOWLING PIN AND HAVING ANENLARGEMENT IN THE NECK SECTION OF THE CORE RELATIVE TO OTHER PORTIONSOF THE CORE DEFINING A SUBSTANTIALLY GREATER AMOUNT OF VERTICAL WOODFIBER ADJACENT THE PIN SURFACE IN THE NECK SECTION OF THE CORE THAN INTHE NECK SECTION OF THE CORE OF THE CORRESPONDING UNIFORMLY PLASTICCOATED WOOD CORE REGULATION SIZE BOWLING PIN AND A GENERALLY UNIFORMDENSITY PLASTIC COATING COVERING AND BRINGING SAID CORE TO REGULATIONPIN SIZE.